Endoscope Incorporating Multiple Image Sensors For Increased Resolution

ABSTRACT

An endoscope or other endoscopic instrument is provided with multiple image sensors incorporated into the distal tip, each capturing a portion of the image provided from an optical imaging system. The output from the multiple sensors is combined and manipulated into a single high resolution image which can then be displayed to the user. A virtual horizon rotation feature is also provided which can rotate a displayed image within a combined field of view including data from the multiple image sensors. Various light directing element designs are provided to direct image light to the multiple sensors.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. Patent Application No.15/400,137, filed Jan. 6, 2017, and entitled “Endoscope IncorporatingMultiple Image Sensors for Increased Resolution,” which is incorporatedherein by reference.

BACKGROUND OF THE INVENTION Field of the Invention

This invention relates to high resolution video endoscopes, and inparticular to a scope using multiple sensors to create high resolutionimages.

Description of the Background Art

The invention relates to optical instruments such as endoscopes,exoscopes, and borescopes having an image sensor assembly at the distalend of the instrument shaft. More particularly, the invention relates toimage sensing systems that can produce a combined image from multipleimage sensors located within the distal end of the instrument shaft, andto optical instruments incorporating such image sensing systems.

Instruments such as endoscopes and borescopes are used to allow a visualinspection of locations which are not readily accessible. For example,endoscopes are typically (although not exclusively) used in medicalapplications to provide a view of an area within a patient's body.Whether employed for medical or other applications, the instrumenttypically includes an elongated shaft of relatively small diameterextending from a handle to a distal end.

An imaging or viewing arrangement is included with the instrument toallow a user to obtain a view from the shaft distal end. Thisarrangement may include a system of lenses and a light conduit throughthe shaft to direct an image from the distal end to an eyepieceassociated with the instrument handle. Alternatively, the imaging orviewing arrangement may include an electronic imaging device at thedistal end of the instrument shaft. Such an electronic imaging devicecollects image data and communicates that data through the shaft andhandle ultimately to a processing system that assembles the data toproduce an image displayed on a suitable display device.

Depending upon the procedure for which the instrument is used, it may benecessary for the operator to view a relatively large area, or view arelatively small area from different angles. In a medical procedure forexample, the operator may desire to view a location which is larger thanthe field of view of the imaging collecting arrangement of the endoscopeor view a location from different angles. In these situations, it hasbeen necessary for the endoscope operator to move the distal end of theendoscope in an effort to provide the desired views, and sometimes movethe distal end repeatedly in given area.

Endoscopes have been developed to give the operator the ability toadjust viewing angle. U.S. Patent Application Publication No.2015/0238068 discloses an endoscope having an objective lens and prismthat is mounted on a pivotable structure at the distal end of theendoscope. This endoscope, however, allows rotation to only one side ofthe device. Thus, the endoscope had to be repositioned in the area ofthe procedure in order to view a location on the opposite side of theendoscope shaft.

U.S. Publication No. 2014/0012080 shows another endoscope with an imagecollecting part which may be tilted to one side of the endoscope at thedistal end. This arrangement also requires the endoscope distal end tobe repositioned to obtain views of areas on the opposite side of theendoscope shaft (that is, opposite the side to which the imagecollecting device is tilted at a given point in time).

A flexible endoscope that allows panning the image without moving thescope tip is found in U.S. Pat. No. 8,771,17762 to Hale et al., which iscommonly owned with the present invention. This scope uses a wide anglelens positioned at an angle to the center axis of the scope to focuslight from the front and sides of the scope. The light is focused on ahigh resolution sensor, along which a desired area is selected toproduce an image that can be digitally panned along the range of viewcovered by the wide angle lens. The scope shaft is flexible and the highresolution sensor is positioned in a distal end portion of the shaft.

U.S. Pat. No. 8,360,964 to Ertas describes a wide angle HDTV endoscopeincludes at least two optical imaging channels. Two lenses are presentat the scope distal tip, having different fields of view incomplementary directions. Received images are transmitted along separateoptical channels along the longitudinal axis of the endoscope to asingle camera head that contains a wide screen image sensing device.

U.S. Publication No. 2015/0062299 describes a relatively large endoscopeincluding two electronic-cameras arranged side-by-side facing alongscope axis to create stereo picture pairs to permit quantitative3-dimensional (3D) imaging and analysis.

U.S. Pat. Nos. 7,783,133 and 7,211,042, and U.S. Publication No.2014/0375784 describe various techniques to counter-rotate an imageproduced from an endoscope image sensor and thereby achieve a constant,user-defined horizon.

Image sensors with desirably high resolution can be too large to fitinto the distal tip of an endoscope. This problem often limits imageresolution for endoscopes. With sensors available at the time of filing,an HD (1080p) sensor of adequate quality can be fit inside a scope shaftof a 10 mm diameter.

There remains a need for ways to provide higher resolution capabilitiesfor endoscopes. There also remains a need in the art to provide anoptical instrument such as an endoscope that allows the imaging deviceto be adjusted so that different views can be obtained without having tomove the instrument distal end, or at least limiting the amount to whichthe distal end must be moved in a given procedure.

SUMMARY OF THE INVENTION

It is therefore an object of the invention to provide higher resolutionand improved image manipulation for endoscopes having distal-tip imagesensors. This invention is an endoscope that has multiple image sensors,each capturing a portion of the optical image provided by an opticalimaging system. The output from the multiple sensors is combined andmanipulated into a single high resolution image which can then bedisplayed to the user. A virtual horizon rotation feature is alsoprovided which can rotate a displayed image within a combined field ofview including data from the multiple image sensors. Various lightdirecting element designs are provided to direct image light to themultiple sensors.

According to a first aspect of the invention, an endoscopic instrumentfor receiving an optical image includes an optical channel assemblypositioned at the distal end portion of the endoscope shaft with alongitudinal axis spanning distal and proximal sides of the distal endportion. An objective lens with negative optical power is positioned inthe distal end portion to receive image light from an object space andpass the image light toward the proximal side. The lens is typically aplano-convex singlet, but may have another optical configuration.

First and second image sensors are positioned in the instrument shaftdistal end portion, the first image sensor positioned to receive a firstportion, but not all, of the image light corresponding to a first areaof an optical image, and the second sensor positioned to receive asecond portion of the image light corresponding to a second area of theoptical image. The second area is at least substantially different fromthe first area.

A first light directing element is positioned in an image space of theoptical channel assembly to receive the first portion of the image lightfrom the optical channel assembly and direct said portion toward thefirst image sensor. The first image sensor is positioned such that thelight directed toward the first image sensor by the first lightdirecting element is imaged onto the first image sensor.

In a first implementation according to the first aspect, a second lightdirecting element is positioned in the image space to receive at leastthe second portion of the image light and direct it toward the secondimage sensor, wherein the second image sensor is positioned such thatthe light directed by the second light directing element is imaged ontothe second image sensor

In some implementations according to the first aspect or implementation,the first light directing element is implemented as a prism or a mirror.The first light directing element may also be a beam splitting prism insome versions.

In another implementation according to the first aspect or aboveimplementations, the optical channel assembly further includes a singlechannel imaging system having one or more lenses optically arrangedbetween the objective lens and the image sensors for passing the imagelight toward the image sensors by directing it to the image space whereit is redirected to the image sensors.

In some implementations according to the first aspect or aboveimplementations, the images on the first and second image sensors atleast substantially overlap. For example, the first portion and secondportion of the image light overlap such that each image sensor receivesthe same area of the image contained within the overlap.

In some implementations according to the first aspect or aboveimplementations, the first and second image sensors at leastsubstantially overlap. In other words, the second image sensor occupiesa space that is mostly (or completely) directly above, in a directionthat is non-parallel to the longitudinal axis, the first image sensor.

In some implementations according to the first aspect or aboveimplementations, a processing unit is operatively coupled to the firstand second image sensors to receive first and second image data from thesensors and operable to combine images from the first and second imagedata into a displayed image of higher resolution than that possible withthe first sensor alone or the second sensor alone. The processing unitmay be further operable to, when a user rotates the endoscopicinstrument around its shaft, rotate a displayed image to provide a viewwith a constant horizon. In optical instrument system embodiments, theprocessing unit may reside, for example, within a camera head or cameracontrol unit.

In some implementations according to the first aspect or aboveimplementations, the first and/or second image sensors is/are positionedbetween 3 mm and 15 mm away from the objective lens.

In some implementations according to the first aspect or aboveimplementations the first and/or second image sensors is/are arrangedsubstantially parallel with respect to the longitudinal axis.

In some implementations according to the first aspect or aboveimplementations, a third image sensor is arranged between the first andthe second image sensors. The first, second, and third image sensors mayat least substantially overlap in a direction that is non-parallel tothe longitudinal axis.

In some implementations according to the first aspect or aboveimplementations, the field of view of the optical channel assembly is atleast 60 degrees. In wide-angle implementations, the optical channelassembly is a wide-angle lens system and may have a field of viewbetween 60 and 180 degrees.

According to a second aspect of the invention, a method is provided forimaging through an endoscope. The method includes receiving image lightat a distal lens of an optical assembly and passing the image lightthrough a single optical channel path toward an image space within adistal end of the endoscope. The method further includes receiving afirst portion of the image light with a first image sensor positioned inthe endoscope distal end, forming a first image of a first part of thefield of view of the distal lens, and receives a second portion of theimage light with a second image sensor, the second portion of the imagelight forming a second image of a second part of the field of view ofthe distal lens, the second part of the field of view at leastsubstantially different from the first part of the field of view.

The method further includes combining the first and second images toproduce an image of higher resolution than would otherwise be possiblewith a single sensor. The method may perform image processing to alignimage data from the two images to allow combining them for a combinedimage stream.

In a first implementation according to the second aspect, the methodfurther includes redirecting the first portion of the image light to thefirst sensor at a non-zero angle to a longitudinal axis spanning thedistal end portion. The angle of redirection may be approximately 90degrees.

In another implementation according to the second aspect or aboveimplementation, redirecting the first portion of the image light isperformed with a prism. Redirecting the first portion of the image lightmay also be performed with a beam splitting prism.

In another implementation according to the second aspect or aboveimplementations, the first and second partial fields of view partiallyoverlap.

In another implementation according to the second aspect or aboveimplementations, the method further includes, in response to a userrotation of the endoscopic instrument around its shaft, conducting imageprocessing to create an image with a constant horizon and of higherresolution than would otherwise be possible with a single sensor. Themethod may also include detecting the user rotation with at least oneposition sensor in the endoscope.

According to a third aspect of the invention, an optical instrumentsystem includes an endoscopic instrument according to any of the aboveaspects and implementations and a camera control unit adapted to receivedata from the endoscopic instrument and may be further adapted toperform one or more of the above implementations. For example, thecamera control unit may include a processing unit to perform imageprocessing for implementing a constant horizon rotating function. Theoptical instrument system may further include an electronic display forreceiving a video signal.

Further scope of the applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes, combinationsand modifications within the scope of the invention, as defined in theclaims, will become apparent to those skilled in the art from thisdetailed description

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a perspective view of an endoscope instrument according to anexample embodiment;

FIG. 2A is a cross section block diagram of a distal end of a shaftaccording to an example embodiment of the invention;

FIG. 2B shows a more detailed example design of a scope distal endportion according to another embodiment;

FIG. 2C shows a light ray bundle diagram for a system like that of FIG.2B;

FIGS. 3A-D are cutout diagrams from various perspectives showing examplesensor placements;

FIGS. 4A-D are cross section diagrams of several example variations ofsensor and light directing element placements in the scope distal endportion;

FIG. 5 is a block diagram of an optical instrument system according toan example embodiment of the present invention;

FIG. 6 is a flowchart of an example process for combining and rotatingthe partial images received from the multiple sensors according to someembodiments;

FIG. 7 is a diagram showing a displayed area selected from within thecombined image sensor field of view according to an example embodiment;

FIG. 8 is a diagram showing digital rotation of a displayed area withinthe combined image sensor field of view to provide a virtual horizon;

FIG. 9 is an example diagram of another display area scheme showing alarger portion of the available combined image area.

DETAILED DESCRIPTION OF THE DRAWINGS

As used herein, elements (e.g., sensors and lenses) that are “opticallyarranged” in relation to other elements, refers to the elements'position along an optical path shared by first and other elements. Forexample, a relay lens group optically arranged between an image sensorand an objective, means that the relay lens group occupies a portion ofthe optical path that light travels (i.e., from the objective to theimage sensor) for capturing images or video. “Optical image” is an imageformed by the light rays from a self-luminous or an illuminated objectthat traverse an optical system or element.

Referring to FIG. 1, depicted is a perspective view of an instrument 100employing multiple distal image sensors according to one aspect of thepresent invention includes an elongated shaft 101 and a handle 102.Shaft 101 extends from a proximal end shown generally at referencenumeral 104 connected to handle 102 to a distal end generally indicatedat reference numeral 105. A distal end portion 106 is included at theshaft distal end 105. The image sensors according to the presentinvention are located in distal end portion 106, although it is notshown in FIG. 1 due to the scale of the figure. The shown shaft 101 is aflexible implementation, but rigid-shaft implementations are alsopossible.

Instrument 100 receives electrical operating power through a cable 108which extends from a proximal end of handle 102 in this exampleinstrument. This power may be used to operate one or more light sourcesand other electronic elements mounted within distal end portion 106,including multiple electronic image sensors. Also, data signals fromsuch an imaging device may be communicated through appropriate conduitswithin shaft 101 and handle 102 to cable 108. These data signals may becommunicated through cable 108 to processing equipment (not shown) whichprocesses the image data and drives one or more video monitors todisplay the images collected at distal end 105 of instrument 100. Thosefamiliar with endoscopes and borescopes will appreciate that instrument100 includes a number of additional features such as controls 110 forcontrolling the operation of the instrument. Although data transmissionrelating to the image sensors will be described further below, thegeneral operation and control of instrument 100 will not be describedfurther herein in order to avoid obscuring the present invention inunnecessary detail. Preferably the designs and techniques herein areemployed as improvements to a videoendoscope with a distal mounted imagesensor arrangement, such as, for example, the videoendoscope describedin U.S. Pat. No. 8,814,782 to Hale, et al, issued Aug. 26, 2014, whichis hereby incorporated by reference.

Referring to FIG. 2A, this figure shows a cross section block diagram ofa distal end of a shaft according to an example embodiment of theinvention. Depicted is the distal end portion 106 of shaft 101 having acover glass 202 in an inset position at its distal face 201. Opticallyarranged at the interior side of cover glass 202 is an optical channelassembly positioned in the distal end portion 106, including anobjective lens with negative optical power 204 having distal andproximal sides positioned to receive image light from an object space(the area to be imaged) at the distal side of lens 204 and pass theimage light to the proximal side.

In wide-angle implementations, the field of view of the optical channelassembly may be between 60 and 180 degrees. Wide-angle implementationsmay include a fisheye lens as an optical element of a wide-angle lenssystem. The wide-angle lens system may be partially- or fully-defined bythe optical channel assembly.

In the embodiment shown, cover glass 202 and lens 204 are fixed at a 30degree angle from the scope axis, however in other versions no angle maybe used or some other angle such as 45 degrees may be used. The opticalchannel assembly typically includes lens 204 and a single channelimaging system 205 of one or more prisms, lenses, lens groups, or otheroptical elements optically arranged at the proximal side of lens 204 toreceive the image light as a beam and focus, disperse, or otherwisemodify the beam. By “single channel”, it is meant that a beam of lightforming a single image is passed through a common lens group or set ofoptical elements with a single perspective.

The optical channel assembly, an example version of which is furtherdescribed with respect to FIG. 2B, generally directs the light toward animage space 211 at the distal end of the optical channel assembly 205.While the space is depicted as a gap in the drawings, a smaller gap orno gap may be present in some implementations. At least two imagesensors 214 and 216 are positioned in the distal end portion 106 toreceive light from the image space.

The upper depicted image sensor 214 is positioned to receive a firstportion, but not all, of the image light corresponding to a first areaof an image observed by the endoscope being redirected by lightdirecting element 12 in the image space of the optical channel assembly,and the second sensor 216 is positioned to receive a second portion ofthe image light redirected in the image space 211 by the second depictedlight directing element 12 and corresponding to second, different areaof the image.

The light directing elements 12 may be any suitable element forredirecting light, such as a prisms, mirrors, light splitters or beamsplitters, or fiber optic elements. Prisms are preferred because oftheir small size, mechanical durability and resistance to deformity.

As can be seen in this example version, the first image sensor 214 ispositioned with a sensor array pointing to receive light propagatingalong a local optical axis non-parallel to the longitudinal axis of theendoscope shaft 203 of the optical channel assembly. In this figure, thesensor array is oriented substantially parallel to a longitudinal axisof the instrument shaft. In a conventional arrangement, shown in FIG.3A, a sensor array is positioned perpendicular to the optical axis ofthe lens group providing the optical image for the array.

The arrangements shown in the other figures, in contrast, allow forsensors of a greater active array area (e.g., a light sensing area) thanwould ordinarily be possible to be fit into the endoscope shaft.Although in FIGS. 2A and 2B image sensors 214 and 216 are orientedparallel to the longitudinal axis of the endoscope 203, with theirsensor arrays oriented for receiving light propagating along a localoptical axis perpendicular to the longitudinal axis of the endoscope203, other non-parallel image sensor pointing angles may be used. Forexample, one or both the sensor arrays may be pointed for receivinglight redirected at 45 degrees from the longitudinal axis of theendoscope, at 30 degrees, or at 60 degrees.

Image sensors 214 and 216 typically are part of at least one sensingmodule or assembly that includes a printed circuit board (“PCB”) onwhich is mounted an imaging device including an image sensor withsensing array, typically having a transparent cover. The PCB or otherelectrical circuitry that reads the sensed signal off the image sensingarray of the sensors may be of any suitable type, preferably thesmallest and lowest profile available to fit in the limited space. Thevarious portions of the sensor assembly are known and are not shownseparately. It will be appreciated by those familiar with imagingsensors that these devices may be accompanied by electronic componentssuch as transistors, capacitors, resistors, and regulators for example.

Additionally, imaging sensors 214 and 216 and their accompanyingelectronic components require electrical power and means forcommunicating image data to be processed for producing the collectedimages. The required operating power and data transmission may beprovided through a suitable electrical cable or bus connection. Theseaccompanying electronic components and the power/data cable are omittedfrom the present drawings in order to more clearly illustrate thevarious features of the imaging apparatus.

Those skilled in the art will appreciate that the electronic componentsand power/data cable may be connected to or included with the imagesensor modules in any number of fashions. For example, some embodimentsmay include the electronic components mounted on the opposite side ofPCB on which imaging sensor itself is mounted. The power/data cable mayalso be connected to the back side of PCB to provide operating power tothe image sensors and allow image data to be communicated from the imagesensor assembly to processing equipment remote from the shaft distal endportion 106. However, the present invention is not limited to anyparticular mounting arrangement for electronic components which mayaccompany imaging sensor and a power/data connection. Any accompanyingelectronic components and the power/data cable need only be mounted toprovide the required function.

Further, although sensors 214 and 216 are shown as discreet entities,two or more of the sensors may be share, for example, a mountingsubstrate or housing accommodating the two or more sensors.

In FIG. 2A, the image sensors 214 and 216 are connected through a powerand data connection to an analog signal processor 22, which receives theanalog sensor data and conditions it for processing by the digitalportions of the system, as will be further described below. An analogsignal processor 22 may be located in the handle 102 (FIG. 1) of thescope device, but may be located elsewhere. It is understood that metaloxide semiconductor sensors (CMOS) type sensors may have incorporatedwith the sensor assembly some of the digitization functions, however ananalog signal processor 22 may provide further signal processing andcontrol is needed before the image data is suitable for digitalprocessing.

FIG. 2B shows a more detailed example design of a scope distal endportion 106 according to another embodiment. Behind the cover glass 202is shown a preferred position for lens 204, set against or very nearcover glass 202 and preferably assembled together with the cover glassin construction and then inserted into a gap in the scope tip from theproximal side and set in place. The single-channel imaging system inthis embodiment includes a deflecting prism 206, or other suitablecompound prism or combination of prisms, optically arranged or attachedat the proximal side of lens 204 to receive the incoming light rays anddeflect them along the longitudinal axis of the endoscope shaft.

This effect can be seen in the diagram of FIG. 2C which shows a lightray bundle diagram for a system like that of FIG. 2B (not to scale).Optically arranged or attached at the proximal side of deflecting prism206 is a lens 208, preferably a convex singlet lens as depicted, tospread the incoming light to an appropriate size for the imaging processdownstream in the proximal direction. Next the light is received at anachromatic doublet lens 210, or other suitable lens, and directedoutward to the image space 211. While this particular optical channelassembly is preferred, any other suitable optical assembly may be usedto prepare the incoming light for reception by the image sensors.

At the image space 211, the light emerges from the single channeloptical system described in parallel or near-parallel rays. In thisembodiment, the image light is directed to the sensors 214 and 216 byright angle prisms 213, which are one example of light directingelements 12.

This arrangement receives a first portion of the image light from theoptical channel assembly with the first image sensor 214, the firstportion of the image light forming a first image of a first part of thefield of view of the (single) optical channel assembly, and receives asecond portion of the image light from the optical channel assembly withthe second image sensor 216, the second portion of the image lightforming a second image of a second part of the field of view of theoptical channel assembly, the second part of the field of viewsubstantially different from the first part of the field of view.

As can be understood, the different portions of light make up differentareas from the common image light fed to image space 211, and providedifferent areas of the image viewable through the scope. The image lightmay be maintained in the same focal conditions through both prisms 213so that the two partial images can be easily reconstructed by havingidentical resolutions. It is not necessary in all embodiments that thetwo prisms 213 or light directing elements 12 or the imaging sensors beidentical or symmetrical. For example, a non-symmetrical embodiment isshown in FIG. 4A.

Referring to FIGS. 3A-3D, several different sensor arrangements aredepicted. In FIG. 3A, a theoretical maximum area square sensor is shownin the conventional configuration with the sensor array orientedperpendicular to the longitudinal axis of the endoscope. The sensor areais approximately 7×7 mm, and is the largest that will fit into a 10 mmcylindrical scope tip 106. Of course, in practice sensors includepackaging and the associated electronics usually included on a circuitboard to which the sensor array is mounted, and so the depictedtheoretical maximum area is not reached in practice.

In reality, 7×7 mm a sensor module will provide an array with a certainpercentage smaller sensor. However, two such sensors can greatlyincrease the image resolution available if they are employed together inalternative positions inside the scope distal end 106, as depicted inthe example diagrams of various embodiments of the in invention in FIGS.3B, 3C, and 3D. FIG. 3B shows a perspective cutaway diagram from besideand forward of a scope distal end 106, with the cover glass and opticscutaway. As can be seen, sensors 214 and 216 are fit into thecylindrical scope tip, and while this does not allow an increased width,it does allow an increased length or height of the total area sensed,which can be as high as the sum of both lengths, L1+L3 as shown.

It is noted that preferably a square sensor is not used, but acommercially available rectangular sensor with an aspect ratio accordingto one of the several HD aspect ratios (such as, for example, the 16:9aspect ratio used for 1920×1080 HD, or the 4:3 aspect ratio used for1440×1080). In such a case, a higher resolution can be achieved byorienting such HD sensors horizontally with respect to the diagramsshown, where for example in FIG. 3B, L1 and L3 is the physical length ofthe 1080 dimension of the sensor array, while the width W is thephysical width of the 1920 dimension of the sensor array. A sensor mayalso be fit favorably in the cylindrical scope distal tip 106 with theshorter dimension of the sensor along the W side, and the longer as theL1 or L3 side.

The prior arrangement may be preferred to provide a sensor field bettermatched to a circular field of view of wide-angle (e.g., fisheye)implementations of the lens 204. Further, while currently the bestavailable sensors sizes for the desired scope diameters (10 mm beingmost common but other diameters are also used such as 4 mm or 5 mm) areHD resolution sensors, future generations such as 4K or UHD sizedsensors may also be placed in the depicted arrangements to increase theimage resolution still further. Further, custom sensors that are squareor have other shapes, including curved sensors (e.g., curved sensorsthat reduce or eliminate Petzval field curvature), may be employedhaving other desired sizes as long as they are able to fit insidewhatever scope diameter is used.

FIG. 3C shows a similar perspective cutaway diagram for the arrangementof FIG. 4A. Sensor 216 has a length L3 and width W, and sensor 218 haslength L1 and width W. Similar to sensor 214, sensor 218 may be squareor have a rectangular aspect ratio such as HD, UHD, 4K, etc., with thepreferred orientation of the shorter sensor array dimension being L1 andthe longer being W, but switching these edges may also be done.

FIG. 3D is a cutaway cross section diagram of another arrangement inwhich three sensors are employed, which may be used to provide an eventaller sensed image allowing electronic panning along the verticaldimension of the field of view or allowing display of an even tallertotal sensed field of view than the improved version of FIGS. 3B and 3C.Of course, in all the embodiments herein, the relative position may berotated around the scope axis with the horizontal resolution increasedrather than the vertical. As depicted, a sensor 214 has length L3,sensor 218 has length L1, and sensor 216 has length L3. Identicalsensors may be used making L1 and L3 identical. The vertical resolutionobtainable with this arrangement is a maximum of the combined verticalresolutions of all of these sensors, L3+L1+L3, while the horizontalresolution remains as the original horizontal resolution along the Wdimension. The arrangement of FIG. 3D may be oriented with the shortersensor array side as L1 or L3, and the longer sensor array dimension asW (the dimension into the drawing).

FIG. 4A is a cross sectional diagram of a scope distal end portion 106mostly similar to that in FIG. 2A, except that a different constructionof light directing elements is employed, which direct light to sensors216 and 218 in a different, non-symmetrical arrangement. The coverglass, lens, and single channel imaging system similar to those of FIG.2A. In this version, a different arrangement of two image sensors, 216and 218, is shown with the sensors positioned as described with regardto FIG. 3C. In this version a right angle or triangular prism 212 ispositioned in image space 211 of the optical channel assembly to receivethe first portion of the image light from the wide angle lens 104 anddirect it toward the image sensor 216, and sensor 218 is positioned toreceive a second portion of the image light corresponding to second,different area of the image. A cube prism or rectangular prism 224 isarranged in front of sensor 218 to help maintain similar focusconditions and path length to the light passing through prism 212.

In some versions, a combined prism similar to prisms 212 and 224 may beused in which a portion of the prism acts as a beamsplitter to allowsome light to pass through straight to sensor 218, while other light isreflected to sensor 216. Such a structure can allow a few rows of pixelstoward the front edge of sensor 216 and the lower edge of sensor 218 toview the same area, allowing a digital image processor to align theimages to combine them more accurately in case of alignment variationsin the prisms or sensors.

FIG. 4B is a cross sectional diagram of another scope distal end portion106, mostly similar to that in FIG. 2A, but with a different type oflight directing element. In this embodiment, a pair of mirrors 222 isused to reflect light from the image space 211 onto sensors 214 and 216.The mirrors may be mounted at a 135 degree angle relative to thelongitudinal axis of the endoscope to reflect light from the image spaceto the sensors with the sensor arrays oriented parallel to the scopeaxis.

FIG. 4C is a cross section diagram of another example scope distal endportion, this embodiment using mirrors as light directing elements. 222to reflect a first portion of the image light upward to sensor 214,reflect a second portion of the image light downward to sensor 216, andallow the middle portion of the sensor light to pass to sensor 218.

FIG. 4D is a cross section diagram of yet another example, in which abeam splitting prism is used as a light directing element. In thisembodiment, a beam splitter prism cube 402 is mounted in the distal end106 to receive the image light from the single channel imaging system.The prism cube 402 may be constructed with suitable prisms to split theincoming light to the two sensors 216 and 218, each positioned toreceive a portion of the image light corresponding to a differentportion of the optical channel assembly field of view.

For example, the prism 402 may be constructed with two right angle prismjoined together, with a dielectric, achromatic beamsplitter coatingalong the interface between the prisms. As can be seen in the light raydiagram, the light is split with 50% of the light reflected downwardwhile the other 50% is passed straight through the prism 402.Alternatively, the reflectivity of the beamsplitter may vary spatiallyso that the portions of light reflected to the two sensors may differfrom one field position to another. Sensor 218 is positioned to receivelight covering at least the upper half of the optical channel assemblyfield of view, while sensor 216 is positioned to receive redirectedlight covering at least the lower half of the optical channel assemblyfield of view. As shown, each sensor receives light from more than halfof the field of view, allowing the images received to overlap so that animage based on the entire field of view may be constructed because thelower-depicted edge of sensor 218 and the left depicted edge of sensor216 receive split versions of the same light rays.

FIG. 5 is a block diagram of an optical instrument system according toan example embodiment of the present invention. While this examplecircuit is shown for an endoscope, the present invention is applicableto more than one type of medical scope instrument, but typically isapplicable for scope applications that employ image capture at theinstrument distal tip, such as endoscopes, borescopes, or exoscopes, forexample.

A light source 8 illuminates subject scene 9 and light 10 reflected from(or, alternatively, as in the case of certain fluorescent or digitalmicroscope arrangements, transmitted or emitted by) the subject sceneforms an optical image via an optical channel assembly 11, where thelight is focused, typically aligned with the scope axis or a desiredoptical axis, and passed to a distal side of optical channel assembly 11where light directing elements 12 direct different portions of the lightto form different portions of the image on two solid-state image sensors14 and 16.

In the present invention, optical channel assembly 11 includes asingle-channel imaging system and may be constructed according to alarge variety of known methods suitable for placement in a scope distaltip, including the preferred optical channel assembly of FIG. 2B. Imagesensors 14 and 16 convert the incident light to an electrical signal by,for example, integrating charge for each picture element (pixel). Theimage sensors 14 and 16 may be active-pixel type complementary metaloxide semiconductor sensors (CMOS APS) or a charge-coupled devices(CCD), to give just two possible examples. The output analog signal fromthe image sensors is processed by analog signal processor 22 and appliedto analog-to-digital (A/D) converter 24 for digitizing the analog sensorsignals. In some versions (typically CMOS designs), the analog signalprocessing and A/D converters may be integrated into individual sensormodels attached to each sensor 14 and 16.

The system's camera 28 generally includes timing generator 26, whichproduces various clocking signals to select rows and pixels andsynchronizes the operation of image sensors 14 and 16, analog signalprocessor 22, and A/D converter 24. One or more motion sensors 13 suchas, for example, an accelerometer, gyro, or magnetometer, may be mountedin the endoscope shaft, tip, or handle to aid in detecting rotation ofthe endoscope. A scope distal tip electronic assembly typically housesimage sensors 14 and 16, while the locations of each of analog signalprocessor 22, the A/D converter 24, and the timing generator 26 mayvary, for example in the scope handle 102 or partially integrated intothe distal tip electronic assembly. The functional elements of thecamera 28 may be fabricated as a single integrated circuit as iscommonly done with CMOS image sensors or they may beseparately-fabricated integrated circuits.

The system controller 50 controls the overall operation of the imagecapture device based on a software program stored in program memory 54.This memory can also be used to store user setting selections and otherdata to be preserved when the camera 28 is turned off. Data connections27 and 29 carry the digital image data of image sensors 14 and 16,respectively, to image processing circuitry 30, which may be integratedwith system controller 50 in some versions, or may be a separateprogrammable logic device or data processor. A data bus 52 provides apathway for address, data, and control signals. In some variations, databus 52 may also carry data connections 27 and 29.

Image processing circuitry 30 performs image processing operationsincluding the operations to combine the partial images from imagesensors 14 and 16, and to perform rotation functions as furtherdescribed below. Processed image data are continuously sent to videoencoder 80 to produce a video signal. This signal is processed bydisplay controller 82 and presented on image display 88. This display istypically an HD, UHD, or 4K format liquid crystal display backlit withlight-emitting diodes (LED LCD), although other types of displays areused as well. The processed image data can also be stored in systemmemory 56 or other internal or external memory device.

The user interface 60, including all or any combination of image display88, user inputs 64, and status display 62, is controlled by acombination of software programs executed on system controller 50. Userinputs typically include some combination of typing keyboards, computerpointing devices, buttons, rocker switches, joysticks, rotary dials, ortouch screens. The system controller 50 may manage the graphical userinterface (GUI) presented on one or more of the displays (e.g. on imagedisplay 88). The GUI typically includes menus for making various optionselections.

Image processing circuitry 30, system controller 50, system and programmemories 56 and 54, video encoder 80, and display controller 82 may behoused within camera control unit (CCU) 70. CCU 70 may be responsiblefor powering and controlling light source 8 and/or camera 28. As usedherein “CCU” refers to units or modules that power, receive data from,manipulate data from, transmit data to, and/or forwards data fromoptical instrument cameras. CCU functionalities may be spread overmultiple units known as, for example, a “connect module”, “link module”,or “head module”.

FIG. 6 is a flowchart of an example process for combining and rotatingthe partial images received from the multiple sensors according to someembodiments, which may be employed with the example hardware and cameradesigns herein, or may be employed with other hardware designated with asimilar purpose, such as software program code executed by a GPU orother image processor. The depicted process starts at block 601 withreceiving image light at a distal lens of an optical assembly andpassing the image light through a single optical channel.

Next at blocks 602, the process redirects a first portion of the imagelight at a non-zero angle to the longitudinal axis of the endoscopetoward the first sensor. A second portion of the image light may also beredirected at a non-zero angle to the longitudinal axis of the endoscopeat block 603, or it may pass straight to the second sensor in someembodiments, so block 603 is has a dotted border as being optional. Ascan be understood blocks 602 and 603 may be performed by two differentlight directing elements or a single light directing element such as acompound prism.

At blocks 604 the process receives the first portion of the image lightfrom the optical channel assembly with the first image sensor, the firstportion of the image light forming a first image of a first part of thefield of view of the distal lens. Simultaneously at block 605 theprocess receives the second portion of the image light from the opticalassembly with the second image sensor, the second portion of the imagelight forming a second image of a second part of the field of view ofthe distal lens, the second part of the field of view substantiallydifferent from the first part of the field of view. The first and secondimages may have a partially overlapping field of view or not.

The depicted process blocks that are in parallel are typically performedwith parallel processing, as are many of the other processing functionsin preferred designs. At blocks 608 and 609, the process may perform oneor more image processing steps, with these shown in dotted lines toindicate it is optional in some embodiments. Next, at block 610, theprocess includes combining the first and second images to produce animage of the combined field of view of the sensors. The combined imagetypically has a higher resolution than would otherwise be possible witha single sensor. This block may include steps to adjust for relativemisalignment of the sensors, such as applying a rotation to image datafrom one or both sensors (preferably provided in calibration of theinstrument), and may include recognizing edges at the edges of the firstand second images so that those edges can by aligned in the combinedimage.

If overlapping pixels are available as described above, the process mayinclude cross-correlating these overlapping pixels to find the highestpoint of alignment, or applying a shift to one or both of the images toaccount for an offset detected in calibration. Such edge detection andcorrelation are known in the art and will not be further described. Thecombined image is then subjected (at block 612) to image processing suchas dynamic range adjustment, filtering, color range adjustment, featurerecognition, and any other suitable image processing techniques forendoscopic imaging.

The combined image or a selected sub-image from the total combined imageare transmitted to an electronic display for display to the operator atblock 614, and may also be recorded and saved with any suitable video orimage recording format. The entire image is then available for viewing,image processing, and manipulation according to any suitable medicalimagery techniques. In some scenarios, the entire combined image may bedisplayed, while in others an HD aspect ratio image smaller than thetotal image may be selected out of the entire combined image fordisplay, allowing panning or rotation of the image. A diagram of such animage may be seen in FIG. 7, in which the combined field of view of afirst sensor 214 and a second sensor 216 are shown each with a differentfill pattern. The circle 130 represents the area of the image lightcoming from the round lens, and it can be seen in the arrangement ofFIG. 5 that in this version the entire view 130 of the lens is capturedby the combination of the two sensors 214 and 216 (or three or moresensors as according to various embodiments discussed above).

Referring again to FIG. 6, while displaying the combined image stream,at block 616 the process detects the physical rotation of the scopedistal end, which may be through sensors such as motion sensors 13 andrecognized by the system controller 50. In some embodiments, detectingrotation may also be done by detecting such rotation in the receivedstream of images through image processing. An operator may set thecurrent orientation as the desired viewing orientation through the userinterface 64 or through a button on the scope handle, for example, afterwhich the process will digitally rotate the display to makecounter-rotations to the displayed images in the opposite direction ofthe scope physical location to maintain ‘virtual horizon’ constantviewing orientation as shown at block 618.

In rotating the display, as shown in the diagram of FIG. 8, the processrotates the displayed view over different portions of the partial imagesreceived from the image sensors, in which the combined field of view ofa first sensor 214 and a second sensor 216 are shown each with adifferent fill pattern. As depicted in this example diagram, an operatorrotating the endoscope in the clock-wise direction causes the process tocounter-rotate the image in the counter-clockwise direction within theavailable field of view, maintaining the view orientation to avoid thecommon problem of operator visual disorientation during examinationprocedures. The opposite physical rotation of course causes an oppositedigital rotation. While this version provides a displayed image areathat is able to maintain the depicted aspect ratio (16:9) whiledisplaying a full image 215 using data from both sensors, otheroperating modes may be provided to display a larger portion of the totalimaged area, or all of the image area.

FIG. 9 shows an example diagram of another display area 215 showing alarger portion of the available combined image area. As can be seen fromthe overlay of the lens field of view 130 on the diagram, this versiondoes not make full use of the lens field of view, but uses more of thesensor data. Digital panning along the combined image may also beprovided in any of the embodiments, in which the up/down arrow shown inFIGS. 7 and 9 shows how a display area may be panned along the availablecombined image data. The vertical direction of the diagram representsthe vertical direction of the wide angle lens field of view in thediagram of FIG. 2A. In some versions or modes, rotation of the view maycause “vignetting” or rounded off dark corners or edges where thedesired display area exceeds the available image data from the combinedimage from the sensors. In some implementations a processing unit maycorrect or modify the distortion characteristics of the image.

Because digital cameras employing endoscopic instruments and relatedcircuitry for signal capture, processing, and correction and forexposure control are well-known, the above description is directed inparticular to elements forming part of, or cooperating more directlywith, a method and apparatus in accordance with the present invention.Elements not specifically shown or described herein are selected fromthose known in the art. Certain aspects of the embodiments may beprovided in software. Given the system as shown and described accordingto the invention in the following materials, software not specificallyshown, described or suggested herein that is useful for implementationof the invention is conventional and within the ordinary skill in sucharts.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the scope of the invention, and all such modifications aswould be obvious to one skilled in the art are intended to be includedwithin the scope of the following claims. For example, reference to anendoscope is intended merely as a representative example application andis not intended to be limiting. Implementations include optical scopessuch as exoscopes and borescopes. Further, although sensors 214, 216,and 218 are shown as discreet entities, two or more of the sensors mayshare, for example, a mounting substrate or housing accommodating thetwo or more sensors.

Further still, although this distribution of imaging device functionalcontrol among multiple programmable logic devices, programmable logicdevices, and controllers is typical, these programmable logic devices,processors, or controllers can be combinable in various ways withoutaffecting the functional operation of the imaging device and theapplication of the invention. These programmable logic devices,processors, or controllers can comprise one or more programmable logicdevices, digital signal processor devices, microcontrollers, or otherdigital logic circuits. Although a combination of such programmablelogic devices, processors, or controllers has been described, it shouldbe apparent that one programmable logic device, digital signalprocessor, microcontroller, or other digital logic circuit can bedesignated to perform all of the needed functions. All of thesevariations can perform the same function and fall within the scope ofthis invention.

What is claimed is:
 1. An endoscopic instrument comprising: (a) a shafthaving a distal end portion and a longitudinal axis spanning distal andproximal sides of the distal end portion; (b) a single optical channelassembly comprising an objective lens with negative optical powerpositioned in the distal end portion to collect image light from asingle perspective of an object space; generate, in an image space, asingle optical image of the single perspective of the object scene; andpass the image light toward the proximal side; (c) a first lightdirecting element positioned within the optical channel at a sufficientdistance from the objective lens such that the first light directingelement is positioned in the image space of the optical channelassembly, the first light directing element positioned to receive afirst portion, but not all, of the image light and direct the firstportion of the image light, corresponding to a first area of the acollected image, along an optical axis that is non-parallel to thelongitudinal axis; (d) a first image sensor positioned in the shaftdistal end portion to receive the first portion of the image light; and(e) a second image sensor positioned to receive a second portion of theimage light corresponding to a second area of the collected image thatis at least substantially different from the first area of the collectedimage.
 2. The endoscopic instrument of claim 1, further comprising asecond light directing element positioned in the optical channel imagespace to receive at least the second portion of the image light anddirect it toward the second image sensor.
 3. The endoscopic instrumentof claim 1, in which the first light directing element comprises a prismor a mirror.
 4. The endoscopic instrument of claim 1, in which the firstlight directing element comprises a beam splitting prism.
 5. Theendoscopic instrument of claim 1, in which the optical channel assemblyfurther comprises a single channel imaging system including at least onelens optically arranged between the objective lens and the first andsecond image sensor.
 6. The endoscopic instrument of claim 1 furthercomprising a processing unit operatively coupled to the first and secondimage sensors to receive first and second image data from the sensorsand operable to combine images from the first and second image data intocomposite image of higher resolution than that possible with the firstsensor alone or the second sensor alone.
 7. The endoscopic instrument ofclaim 6 further comprising a motion sensor, wherein the motion sensoroperable to detect rotation about the longitudinal axis of the distalend portion.
 8. The endoscopic instrument of claim 7 further comprisinga display unit, and wherein the processing unit is further operable toprocess the collected image data enabling the display unit to display animage with a constant horizon.
 9. The endoscopic instrument of claim 1,wherein the first portion and second portion of the image light overlap.10. The endoscopic instrument of claim 1, further comprising a thirdimage sensor arranged between the first and the second image sensors.11. A method of providing endoscopic images comprising the steps ofcollecting, with a distal lens of an optical assembly, image light at asingle perspective from an illuminated object space; directing thecollected image light into an image space along an optical path of theoptical assembly; directing a first portion, but not all, of the imagelight within the image space along an optical path that is not parallelto that of the optical assembly; capturing the first portion of theimage light with a first image sensor; capturing a second portion of theimage light, at least substantially different from the first portion ofthe image light, with a second image sensor; and combining, with animage processor, the first and second images to produce an image ofhigher resolution than would be possible with a single sensor.
 12. Themethod of claim 11 wherein directing the first portion of the imagelight is performed with a prism.
 13. The method of claim 12 wherein thedirection is performed by a beam splitting prism that passes a portionof the first portion of the image light to the second sensor.
 14. Themethod of claim 11 wherein the first and second portions of image lightpartially overlap.
 15. The method of claim 11, further comprising, inresponse to a user rotation of the endoscopic instrument around itsshaft, processing collected image data to create an image with aconstant horizon and of higher resolution than would otherwise bepossible with a single sensor.
 16. An endoscopic instrument comprising:(a) a shaft having a distal end portion with an inner diameter and alongitudinal axis spanning distal and proximal sides of the distal endportion; (b) a single optical channel assembly comprising an objectivelens with negative optical power positioned in the distal end portion tocollect image light from a single perspective of an object space;generate, in an image space, a single optical image of the singleperspective of the object scene; and pass the image light toward theproximal side; (c) a first image sensor comprising an image sensingactive area mounted on a circuit board, the circuit board having adiagonal length longer than the inner diameter of the of the distal endportion; (c) a first light directing element positioned within theoptical channel at a sufficient distance from the objective lens suchthat the first light directing element is positioned in the image spaceof the optical channel assembly, the first light directing elementpositioned to receive a first portion, but not all, of the image lightand direct the first portion of the image light, corresponding to afirst area of the a collected image, along an optical axis that isnon-parallel to the longitudinal axis; and (e) a second image sensor,comprising an image sensing active area mounted on a circuit board, thesecond image sensor positioned to receive a second portion of the imagelight corresponding to a second area of the collected image that is atleast substantially different from the first area of the collectedimage; wherein the first image sensor is positioned in the shaft distalend portion to receive the first portion of the image light.
 17. Theendoscopic instrument of claim 16 wherein the second image sensorcomprises a second image sensing active area mounted on a second circuitboard, the second circuit board having a diagonal length longer than theinner diameter of the of the distal end portion, and wherein theendoscopic instrument further comprises a second light directing elementpositioned within the optical channel at a sufficient distance from theobjective lens such that the second light directing element ispositioned in the image space of the optical channel assembly, thesecond light directing element positioned to receive the second portionof the image light and direct it along an optical axis that isnon-parallel to the longitudinal axis.
 18. The endoscopic instrument ofclaim 17 wherein (a) the first image sensor is rectangular with a heightL1 and a width W1, and with an image sensing active area with a heightl1 and a width w1; (b) the second image sensor is rectangular with aheight L2 and a width W2 and with an image sensing active area with aheight l2 and a width w2; wherein the values of W1 and W2 are bothindividually smaller than the inner diameter of the distal end portion,and wherein L1+L2 is greater than the inner diameter of the distal endportion.
 19. The endoscopic instrument of claim 17 further comprising athird image sensor positioned to receive a third portion of image light,the third portion of image light at least substantially different fromthe first portion of image light and the second portion of image light.20. The endoscopic instrument of claim 16 further comprising an imageprocessing circuitry operable to combine image data received from thesensors into a single image representing an image of the captured singleperspective of the object space.
 21. The endoscopic instrument of claim18 wherein the single optical image in image space is circular with adiameter, D, and wherein D is greater than the values of l1 and l2; D isless than or equal the value of w1 and w2; and D is less than or equalto l+l2.